The telecommunications industry is currently undergoing a massive shift from wired telecommunications devices to wireless devices. The impetus for this transition is mobility, and reduced cost for system reconfiguration. The invention described herein fits the form and function of a "Personal Communications Services" as described in industry terms.
Cellular and other wireless telephones offer mobility, but at the expense of reliability, and interoperability. Additionally, wireless handsets provide unlimited access to the carrier of the telephone and lacks a mechanism for incorporating standard call coverage tools which are provided by the land based telecommunications systems (PBX or Centrex).
Unreliable Connections
Cellular and wireless handsets often lose connection. This is due to many technical reasons, including improper handoff between cells, signals below minimum thresholds, loss of battery power, etc. Typically, upon a lost connection, the caller and wireless user must re-establish communication manually.
Limited Access Screen
Most business telephone extensions are part of the organization's coverage plan. This coverage plan may include, but is not limited to, live operator support, secretary or co-worker coverage, voicemail, etc. Most business phones have buttons for "Do Not Disturb", and many have display screens to identify the (internal) calling party's number and name, if available. Many executives have all arriving calls screened by their secretary, limiting direct access to the executive only for important calls.
The rapid growth in wireless device availability complicates the picture. Cellular telephones are not integrated with any organization's telephone system, as the service is only sold and operated from off-premise locations reached via Central Office connections. A few other wireless devices have recently been made available to the Customer Premise Equipment marketplace to provide on-premise, wireless handset capability. These newer devices provide only simple analog interfaces, with a limited set of capabilities. Some manufacturers offer different levels of integration, but none provide direct determination of unknown callers, and the ability to "act on" the calls.
The lack of integration of wired and wireless telephones means that, for a cellular or cordless user:
No information about who is calling is transmitted to the handset. PA1 There is no ability to screen the caller without answering. PA1 Some wireless devices may be incapable of the "transfer" feature to move the call to another terminal. PA1 Some wireless devices may not be capable of forwarding from the handset to another dialed number. PA1 Calls can't be forwarded or transferred from the on-premise networks to an off premise wireless devices phone. PA1 CCITT Q.700: Introduction to CCITT SS7 PA1 CCITT Q.775: Guidelines for Using Transaction Capabilities PA1 CCITT Q.724: Signaling Procedures PA1 CCITT Q.761: Functional Description of the ISDN User Part of SS7 PA1 TR-NWT-000246 Issue 2, Revision 2: Bell Communications Research Specification of Signaling System Number 7 PA1 SR-NPL-001509 Issue 1: Advanced Intelligent Network Release 1 Proposal PA1 SR-NPL-001623 Issue 1: Advance Intelligent Network Release 1 Network and Operations Plan
The next generation devices, now just reaching the market, include "wireless Centrex" offerings, which use SS7 Common Channel Signaling protocols to integrate Centrex telephones into a Centrex partition. These services are not commonly available due to the slow deployment of the SS7 overlay signalling network into central offices.
Handoff/Transfer Between Cellular and Wired Telephones is Impossible
When a call arrives on a wireless device, the user of the device has the mobility to move from place to place. However, because wireless devices are not "secure", and the quality of the voice may be less than that of a wired telephone, it may be desirable to switch the call to the nearest wired telephone, but only without losing connection. This has the added effect of saving money, since many wireless service providers charge for all air time.
The current art supports automatic handoff between different wireless systems which are homogeneous and support the cellular telephone protocol IS-41 ("roaming"). Unfortunately, handoffs to wired, or dissimilar wireless networks currently was impossible until the development of the current apparatus.